Li Wantong, Migliavacca Mirco, Miralles Diego G, Reichstein Markus, Anderegg William R L, Yang Hui, Orth René
Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, Jena, Germany.
European Commission, Joint Research Centre (JRC), Ispra, Varese, Italy.
Glob Chang Biol. 2025 Jan;31(1):e70035. doi: 10.1111/gcb.70035.
Terrestrial vegetation is a key component of the Earth system, regulating the exchange of carbon, water, and energy between land and atmosphere. Vegetation affects soil moisture dynamics by absorbing and transpiring soil water, thus modulating land-atmosphere interactions. Moreover, changes in vegetation structure (e.g., leaf area index) and physiology (e.g., stomatal regulation), due to climate change and forest management, also influence land-atmosphere interactions. However, the relative roles of vegetation structure and physiology in modulating land-atmosphere interactions are not well understood globally. Here, we investigate the contributions of vegetation structure and physiology to the coupling between soil moisture (SM) and vapor pressure deficit (VPD) while also considering the contributions of influential hydro-meteorological variables. We focus on periods when SM is below normal in the growing season to explicitly study the regulation of vegetation on SM-VPD coupling during soil dryness. We use an explainable machine learning approach to quantify and study the sensitivity of SM-VPD coupling to vegetation variables. We find that vegetation structure and physiology exert strong control on SM-VPD coupling in cold and temperate regions in the Northern Hemisphere. Vegetation structure and physiology show similar and predominant negative sensitivity on SM-VPD coupling, with increases of vegetation dynamics leading to stronger negative SM-VPD coupling. Our analysis based on Earth system model simulations reveals that models largely reproduce the effect of vegetation physiology on SM-VPD coupling, but they misrepresent the role of vegetation structure. This way, our results guide model development and highlight that the deeper understanding of the roles of vegetation structure and physiology serves as a prerequisite to more accurate projections of future climate and ecosystems.
陆地植被是地球系统的关键组成部分，调节着陆地与大气之间的碳、水和能量交换。植被通过吸收和蒸腾土壤水分影响土壤水分动态，从而调节陆地 - 大气相互作用。此外，由于气候变化和森林管理导致的植被结构（例如叶面积指数）和生理特征（例如气孔调节）的变化，也会影响陆地 - 大气相互作用。然而，全球范围内对植被结构和生理特征在调节陆地 - 大气相互作用中的相对作用尚不清楚。在此，我们研究植被结构和生理特征对土壤湿度（SM）与水汽压差（VPD）耦合的贡献，同时考虑有影响的水文气象变量的贡献。我们关注生长季节中土壤湿度低于正常水平的时期，以明确研究土壤干燥期间植被对SM - VPD耦合的调节作用。我们使用一种可解释的机器学习方法来量化和研究SM - VPD耦合对植被变量的敏感性。我们发现，植被结构和生理特征对北半球寒冷和温带地区的SM - VPD耦合具有很强的控制作用。植被结构和生理特征对SM - VPD耦合表现出相似且主要为负的敏感性，植被动态增加会导致更强的负SM - VPD耦合。我们基于地球系统模型模拟的分析表明，模型在很大程度上再现了植被生理特征对SM - VPD耦合的影响，但它们错误地呈现了植被结构的作用。通过这种方式，我们的结果为模型开发提供了指导，并强调对植被结构和生理特征作用的更深入理解是更准确预测未来气候和生态系统的先决条件。
